In 10g and before, the command was oradebug dump events 1 and the list was dumped in a trace file, 11g directly outputs to the console.

Note there is no backward compatibility with unsupported tools like oradebug.
In 11g you will get an ORA-76 with dump events

SQL> oradebug setmypid
Statement processed.
SQL> oradebug dump events 1
ORA-00076: dump EVENTS not found
$ oerr ora 76
00076, 00000, "dump %s not found"
// *Cause: An attempt was made to invoke a dump that does not exist.
// *Action: Type DUMPLIST to see the list of available dumps.